etw: update prototypes to match dtrace provider

The DTrace probes were updated to accomodate platforms that can't
handle structs, update the prototypes for ETW but it's not necessary
to do anything with the new arguments as it's redundant information.

@sblom or @piscisaureus can you please verify that ETW still works?

BTW I've incentivized you by making the build fail on windows without a change